If you look back in 2016 the thing that kept the late rally of 2015 going was the halving that happened in July 2016, see below how the halving led to 2 subsequent rallies.
https://www.coindesk.com/bitcoin-halving-2016-will-price-rise-fall/
It's extremely important to realize the scarcity built into bitcoin and how it reflects digital gold, once you understand this you can hold with confidence even at huge losses because you know that alot later, years later, the price will be much higher.
Keep an eye on when the next halving will be (2020):
https://www.bitcoinblockhalf.com/
But also keep in mind that good news could come out too that could really make the price go parabolic.
But if you invest and hoping to get rich quick, then sorry to burst the bubble, your are in the wrong market. No one can tell you when will Bull runs starts because if you just look at the current sentiments, we are struggling. So it might be next month or next year. I suggest you just stay with the market and wait till the bull run happens.
OP just asked in general when do people think the next bull run in bitcoin will start, not your opinion on whether or not you think he is a newb and if he invested more than he is willing to lose, how about next time you actually give an educated response to his post instead of just rambling about stuff he/she already knows and make them feel worse about their loss.
The thing with the halving is, it is always a very hyped event and naturally one that will raise the price as it is a guaranteed decrease in inflation of the supply, and since it is something that we can guesstimate, people may try to take a move before the next guy because of how market psychology works.
This can lead into a chain reaction which would make this pump start and potentially peak up to a month or more ahead of the actual event, which could lead to a crash by and by the time actual event happens (so a typical sell the news situation), that could mark the end of the crash and the start of the next bull run. Just have that on mind because you may need to plan ahead if you want to risk trading. Personally I may not even bother and just keep holding. Just thinking about going to fiat will lead to having to get ready endless paperwork for taxes and so on which I have no idea how to manage so I would need to pay an accountant... I don't have time for that.